A pilot study is proposed to examine the effects of prolonged social isolation and stress on psychological function. Dodge Morgan is currently attempting to circumnavigate the globe, by himself, non-stop, in a specially designed 60' sloop. Realizing the potential wealth of knowledge to be gained by carefully studying the human response to a period of 7 or 8 months that include elements of social isolation, sleep deprivation, and sensory deprivation and bombardment, Morgan volunteered to participate in a quantitative psychological investigation. The study, which has been designed and is currently underway, consists of 3 phases. The first phase, which has been conducted, entailed an extensive psychological and neuropsychological evaluation of Morgan, which will serve as a baseline against which to compare data from the remaining phases. The second phase of the project entails the self-administration by Morgan of psychological tests on a daily basis while at sea. Mood states, cognitive function, imaginal processes, and sleep behavior are being periodically assessed. Also being obtained are video and audio recordings that objectively monitor in vivo overt behavior and verbalizations as well as environmental and boat conditions. Satellite monitoring, throughout the voyage, will provide objective indices of weather conditions and boat locations, as well as navigational skills and sailing efficiency. The final phase of the project will entail re-administering the extensive psychological evaluation which was conducted prior to the voyage. The final evaluation will be administered immediately after the voyage as well as 4, 8, and 12 months later to assess longer-term aftereffects. The study represents the most complete, quantitative attempt to assess the psychology of long-distance sailors ever conducted, and will serve as a basis for future assessments of sailors on similar voyages in an attempt to increase the data base.